A 48-year-old man was detained at the scene and authorities, including British Prime Minister Theresa May, were quick to condemn the attack as a terrorist act.

May promised to protect the country's mosques while calling the attack an assault on the UK's fundamental freedoms.

"This morning we have seen a sickening attempt to destroy those freedoms, and to break those bonds of citizenship that define our United Kingdom," she said. "It is a reminder that terrorism, extremism and hatred take many forms, and our determination to tackle them must be the same whoever is responsible."

Authorities have not named the alleged attacker, who was arrested on suspicion of murder after he was found detained by members of the public at the scene.

One eyewitness described the horrific scene to reporters as "done vindictively."

"Well, I saw a lot of fatalities on the ground, you know. People moaning," the witness said. "I've never heard people scream and moan of that nature. Some wasn't moaning, some was just on the floor, you know, as though they were dead, you know. I never went and basically found out if they were dead or not, you know."

Eight people injured were taken to three separate hospitals while two people were treated at the scene for minor injuries, according to London's Metropolitan Police.

Due to the nature of this incident, police said they have deployed extra resources in order to reassure communities, especially those observing Ramadan.

In a statement, London Mayor Sadiq Khan said he hopes these steps will "reassure communities" in the midst of observing the holy days of Ramadan.

"While this appears to be an attack on a particular community, like the terrible attacks in Manchester, Westminster and London Bridge, it is also an assault on all our shared values of tolerance, freedom and respect," Khan said.